The present invention relates to well drilling operations and, more particularly, to an apparatus for assisting in the assembly, disassembly and handling of tubular strings, such as casing strings, drill strings, and the like.
The drilling of subterranean wells involves assembling tubular strings, such as casing strings and drill strings, each of which comprises a plurality of elongated, heavy tubular segments extending downwardly from a drilling rig into a well bore. The tubular string consists of a number of tubular segments, which threadedly engage one another.
Conventionally, workers use a labor-intensive method to couple tubular segments to form a tubular string. This method involves the use of workers, typically a “stabber” and a tong operator. The stabber manually aligns the lower end of a tubular segment with the upper end of the existing tubular string, and the tong operator engages the tongs to rotate the segment, threadedly connecting it to the tubular string. While such a method is effective, it is dangerous (especially since both the “stabber” and the “tong operator” typically work on elevated platforms), cumbersome, and inefficient. Additionally, the tongs require multiple workers for proper engagement of the tubular segment and to couple the tubular segment to the tubular string. Thus, such a method is labor-intensive and therefore costly. Furthermore, using tongs can require the use of scaffolding or other like structures, which endangers workers.
Others have proposed a running tool, utilizing a conventional top drive assembly for assembling tubular strings. The running tool includes a manipulator, which engages a tubular segment and raises the tubular segment up into a power assist elevator, which relies on applied energy to hold the tubular segment. The elevator couples to the top drive, which rotates the elevator. Thus, the tubular segment contacts a tubular string and the top drive rotates the tubular segment and threadedly engages it with the tubular string.
While such a tool provides benefits over the more conventional systems used to assemble tubular strings, such a tool suffers from shortcomings. One such shortcoming is that the tubular segment might be scarred by the elevator dies. Another shortcoming is that a conventional manipulator arm cannot remove single joint tubulars and lay them down on the pipe deck without worker involvement.
Accordingly, it will be apparent to those skilled in the art that there continues to be a need for an apparatus that efficiently couples a tubular segment with a tubular string and handles the tubular string within the well bore utilizing an existing top drive. The present invention addresses these needs and others.